JAMUNDÍ, COLOMBIA
— Arcesio Morales Buitrago is in charge of the keys at Mi Casita. A soft-spoken man diagnosed as schizophrenic, he is the doyen of the patients at the leafy psychiatric home.

On May 22, right after the Monday afternoon bingo game, three cars skidded to a halt on the road that dead ends at Mi Casita. Ten men in blue jeans and police vests and one man in a ski mask piled out.

As he reached the green iron gate, however, Sergio Berrio, the administrator of the home, leaned out from the balcony above and screeched: "Stay back! Don't open!"

Morales froze. That's when the shooting started: a torrent of bullets and grenades rained down on the police from the nearby forest. "The war came here," Morales recalls incredulously, "...all the way here."

What followed in the next 45 minutes was the calculated massacre of one of Colombia's best counternarcotics police teams – all hand-picked and trained by the US. None survived.

This is a story of those policemen – of the members of Colombia's military that killed them – and of the narcotraffickers that, according to Colombia's attorney general, ordered the hit.

The investigation of the Jamundí massacre to date suggests the reach that Colombia's drug lords maintain today, and has shaken officials in Washington and Bogotá. The US Congress has temporarily frozen funding for Plan Colombia, the $4.7 billion effort to stop the illicit drug trade – and a chorus of disappointed and angry voices in both capitals is demanding an honest evaluation of the US' most expensive foreign aid program outside of the Middle East, six years after it set out to win the war on drugs.

* * *

"Three thousand Americans a year die from Colombian drugs," says US Ambassador to Colombia William Wood. "That's like suffering a World Trade Towers attack every year."

Talking about drugs in terms of an attack on the US is not new. President Richard Nixon coined the term "war on drugs" in 1971, and President Ronald Regan popularized it in the 1980s, as crack cocaine was devastating America's inner cities. Then, with the cold war drawing to a close, illicit substances and those who trafficked them became the new international enemy – and the countries that produced them became battlefields. Colombia has emerged as the biggest battlefield of all.

An estimated 5.5 million Americans have used cocaine at least once in the past 12 months, roughly the same number as were doing so in 2002, according to the annual US Department of Health and Human Services survey. More than 2.3 million Americans are "current" users, defined as consuming the drug within the last month – a slightly higher number than the regular users counted in 2002.

Cocaine consumption is rising faster in Europe, but the US still has the highest rate of cocaine use anywhere in the world.

And while Ambassador Wood's 3,000 US deaths related to cocaine use is debated, the source of the narcotic is not. Colombia supplies an estimated 80 percent of cocaine worldwide, and more than 90 percent of the cocaine (and half the heroin) in the US, according to the State Department.

Three years after President Reagan defined drugs as a national security threat, President George H. W. Bush intensified this war. Under the 1989 Andean Initiative, aid to the region was boosted and US training and support for counter narcotics military and police was sanctioned.

Bolivia and Peru, the world's two other major coca-producing nations, received sharply increased assistance too – but the majority of the drug-war funds went to Colombia. In 1989, Colombia got $18 million for military and police assistance. A year later, US funding increased five-fold, making it the Western Hemisphere's No. 1 recipient of US security assistance, a distinction it maintains today.

Plan Colombia, the counternarcotics program conceived by Colombian President Andres Pastrana, modified and launched by President Bill Clinton in 2000, and since embraced by President George W. Bush, carried this commitment to new levels.

In its first 18 months, Plan Colombia spent $1.3 billion in the region, the vast majority – $860 million – in Colombia. Of that aid, some 75 percent – $642 million – went toward security – including the formation of a new counternarcotics brigade within the Colombian army whose job was to ease the way for the massive aerial herbicide spraying of coca crops. Since its launch, Plan Colombia has cost the US $4.7 billion, of which 75-80 percent has gone to the security forces.

The plan has achieved significant results in terms of coca fields eradicated, clandestine drug laboratories burned and tons of drugs seized. Thousands of people involved in the drug trade have been caught, killed, put behind bars, or extradited to the US.

Further, the decades-old drug-fueled conflict between right-wing paramilitaries, leftist guerrillas, and the government has abated perceptibly, say analysts. A halting process of demobilizing the paramilitaries is under way, and the rebel Revolutionary Armed Forces of Colombia (FARC) has lost ground to the army. President Alvaro Uribe was re-elected this May in a landslide thanks to his success in improving security in the country.

But the drug trade and the war against it continue to spawn violence, massive displacements of population, and high levels of corruption here, tearing at the social fabric of the country. And Colombia continues to be heavily, some say dangerously, militarized, with its army taking on internal security roles that would be prohibited in the US and many other democracies.

Now the Jamundí ambush is forcing some officials in Colombia (the No. 1 producer of cocaine in the world) and the US (the No. 1 consumer) to reevaluate their approach.

"We have spent $4.7 billion in Colombia ... and we brush under the rug a host of uncomfortable questions – about the military ... degrees of corruption, and overall efficacy of the drug war effort," says Bruce Bagley, an expert on drug trafficking at the University of Miami. "And then, along comes a Jamundí and calls the entire presumption of this war on drugs into question."

* * *

When the shooting started near the psychiatric home, Morales dove into a wide gutter along the driveway, covering his ears with his hands and pressing his face as close to the concrete as he could bear. When he finally emerged, he saw more than a dozen Colombian soldiers from the alpine battalion of the Army's 3rd Brigade descending from the hills. On the ground outside the gate were 11 bodies, riddled with bullets.

"They were my most effective, trustworthy, elite group," laments Brig. Gen. Oscar Naranjo, director of the judicial police. Seven of the men in the team were members of the police's top counternarcotics unit: a group of approximately 200 police who have gone through rigorous vetting and training by the US Drug Enforcement Administration (DEA).

Those seven killed in Jamundí were part of a 15-person team that had, in the past 18 months, smashed 15 drug rings, captured 205 traffickers, including 23 wanted for extradition to the US, and seized nearly 4.4 tons of cocaine.

That day in May, they had come to the Cauca Valley, 195 miles southwest of the nation's capital, together with an informant and three police specialists, on a tip that 440 poundsof cocaine were stashed in the psychiatric home.

A tragic case of "friendly fire," is how Army commander Gen. Mario Montoya originally described the "shoot out," protesting that the troops had no advance knowledge of an undercover operation and had mistaken the police for kidnappers.

But as the smoke cleared, a different narrative began to take shape.

"This was not a mistake, this was a crime; this was a deliberate decision, a criminal decision," Attorney General Mario Iguarán announced a few days later. The soldiers, he bluntly charged, "...were doing the bidding of a drug trafficker." Eight of the policemen were shot in the head, and two were shot in the back, according to forensic reports. "This is one of the gravest cases in our history," says General Naranjo. "This is active corruption, and my men are dead. This cannot be tolerated."

According to a senior official investigating the case, speaking on condition of anonymity, the police unit that day may have been looking not just for drugs, but for a specific drug trafficker: Diego Montoya Sánchez, a reputed head of the Norte del Valle (North Valley) cartel.

Since the dismantling of the Medellín and Cali cartels in the 1980s and early 1990s, the Norte del Valle Cartel has become Colombia's most powerful drug ring. Officials say that the two factions of the cartel are behind 30 percent of the cocaine sent to the US, and Montoya is on the FBI's 10-most-wanted list, right beside Osama bin Laden, with a bounty of $5 million on his head. According to the investigator, the police unit had been told Montoya was hiding in the psychiatric home, posing as a patient.

The Mi Casita administrators, who lost almost half their private funding after the media reports linked them to Montoya, deny any connection to narcotrafficking. The police investigation has turned up no drugs or evidence that a drug lord had been at the home. The police, says the investigator, may well have been on a wild goose chase set up by the army unit, acting on behalf of Montoya.

Fifteen soldiers, including rising Army star commander Col. Bayron Carvajal, were soon arrested – and the investigation, say officials in the attorney general's office, is likely to reach higher in the military ranks and will possibly include the police or even politicians.

Colonel Carvajal's younger brother, Juan Carlos, maintains the soldiers' innocence, suggesting instead the police might be the corrupt ones in the story. "Uribe needed to blame someone," says Carvajal, arguing that Colombia's president could not afford to have the DEA's top trained police unit implicated in any scandal – especially not in late May, right before the presidential elections. "My brother and the others are political pawns. They are being made to take the fall," he insists.

In fact, Carvajal's allegations are not considered to be too far a stretch – the Norte del Valle group is known for its connections to the police. Former cartel leaders such as Danilo González, Victor Patiño, and Patiño's half-brother Luís Ocampo were all former policemen – as is Wilber Varela, currently Montoya's biggest internal rival.

But, evidence against the soldiers is mounting. The most damning is a series of electronic text messages allegedly sent between Carvajal – who was not at Jamundí at the time – and his lieutenant on the ground immediately before the massacre. "Everything is set for tonight," reads one message leaked by authorities. "Get ready for the group to come with the chicken so you can get it," reads another, referring to the nickname of the civilian informant who was leading the police that day.

And now, one senior official close to the investigation says investigators have heard a tape recording of Carvajal speaking on the phone with narcotraffickers to arrange payment for his defense lawyers.

"Jamundí is the tip of the iceberg," says Professor Bagley, arguing the massacre is indicative of the serious gap between Plan Colombia's promise to train a modern, professional military and the realities of the day. The events of that May afternoon, he says, should serve as a serious wake-up call: "This is a disaster for [President] Uribe and Plan Colombia."

At Mi Casita, more than three months later, many of the patients remain traumatized by the massacre. One woman yells out "Police, police...open up!" at the slightest provocation. Another bites herself whenever she hears loud bangs. And Morales, the only eyewitness to the killings, hears the voices of the policemen crying out for mercy when he tries to sleep at night. "Was it my fault?" Morales asks, wringing his hands. "I talk to my saints and ask them for forgiveness."

Mr. Berrio, the administrator at Mi Casita tries to calm Morales, "We can't escape this war. And we can't win it either," he consoles the flustered man and himself at once. "But you did the best thing you could. You kept your head down. That's all any of us would have done."

• Coming next: Is Plan Colombia working?

Why Diego Montoya Sánchez is worth $5 million to the FBI

He likes fast cars (but police seized his personal mini racetrack last year, along with 74 ranches and eight houses). He has a flare for the macabre (his men once ambushed a rival group and then piled the corpses in a pyramid on a road). And, he reportedly likes it when people call him "El Señor de la Guerra," or Mr. War.

Heavyset and gruff, Diego Montoya Sánchez is one of the reputed leaders of Colombia's Norte del Valle cartel. He has a $5 million bounty on his head and is on the FBI's "10 most wanted list" for drug trafficking, conspiracy to import with intent to deliver drugs to the US, money laundering, and racketeering.

In the late 1990s, the Norte del Valle cartel – named for a valley in western Colombia – trafficked about half of the cocaine sold in the US. Today, officials estimate that the cartel holds about 30 percent of the market.

For the past two years, the cartel has been riven by a brutal internal power struggle between Mr. Montoya and his rival Wilber Varela, a.k.a. "Jabon" or Soap. Each faction leader has turned to different sides of Colombia's civil war for support: Varela is reportedly allied with the guerrillas of the Revolutionary Armed Forces of Colombia (FARC). Montoya reportedly has ties to the right-wing paramilitaries.